High Efficiency R-134a Compressor for Domestic Refrigerator

Purdue University Purdue e-pubs International Compressor Engineering Conference School of Mechanical Engineering 1996 High Efficiency R-134a Compressor for Domestic Refrigerator D. S. Kim Samsung Electronics Co. G. G. Kim Samsung Electronics Co. S. T. Lee Samsung Electronics Co. Follow this and additional works at: http://docs.lib.purdue.edu/icec Kim, D. S.; Kim, G. G.; and Lee, S. T., "High Efficiency R-134a Compressor for Domestic Refrigerator" (1996). International Compressor Engineering Conference. Paper 1104. http://docs.lib.purdue.edu/icec/1104 This document has been made available through Purdue e-pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at https://engineering.purdue.edu/ Herrick/Events/orderlit.html

HIGH EFFICIENCY R-134a COMPRESSOR FOR DOMESTIC REFRIGERATOR D. S. KIM, G. G. KIM, S. T. LEE SAMSUNG ELECTRONICS CO.LTD., REFRIGERATOR DIVISION Paldal-gu,Suwon Cit~ Kyungki-Do, Korea ABSTRACT Because of high growth in economy and rapid increase in energy consumption, the government has made efforts to resolve the difficulties of the shortage of energy by restricting the amount of electrical energy consumption for home electrical products and several products consuming energy. Especially, the rules specified how the amount of electrical energy consumption was tested is expected to revise since 1996,and so the situation in grade expressed the efficient consumption of energy has been developed unfavorably since the electrical energy consumption per month was measured more 30% in amount than that used to be when testing the amount of electrical energy consumption for the same model of a refrigerator in according to the revised rules. INTRODUCTION In general, a compressor which consists of the heart of a refrigerator, a heater which removes frost,and a fan-motor which can distribute chill equally are considered as the main causes of consumption input in a refrigerator. Among the above components, improving the energy efficiency ratio of a compressor that has occupied 80 through 85 percent of the total electrical energy can decrease the amount of electrical energy consumption for a refrigerator. Therefore, we want to specify the studied and developed results about the high efficiency of the reciprocating type of a compressor for R-134a. HOW TO PROGRESS C.O.P (Coefficient of performance) In general, in order to progress the efficient of a compressor for a refrigerator, each element such as volume efficiency, compression efficiency,mechanical efficiency and motor efficiency shall be improved. In order to achieve the high efficiency of a compressor as the above specified contents, the cooling capacity shall be increased and the consumption input shall be decreased. So, we can make the cooling capacity be enhanced up to 15% and E. E. R be enhanced up to 9% in contrast with the existing R-12 model by selecting the items which the high efficient effects are anticipated and handling theory with experimental data together on the basis of the above specified theory. 187

THE MAIN SUBJECT 1. Improving the mechanism of valve and valve plate assy In order to decrease the loss, the moving mechanism and the lift magnitude of a discharge valve have been made smooth and optimized respectively, the shape of valve plate's flowing path has been improved(directize), the plenum of discharge gas has been increased, and the heat emitting mechanism of cylinder head has been improved in design. therefore, E. E. R has been enhanced up to 4% by improving the loss of overpressure and pressed heat-transfer. The details for the improved contents are shown in Fig 1 and 2. Also,since the open time of a valve quickened and its close time was delayed in contrast with the conventional model as shown in Fig 3 by improving the discharge valve system, we have known the total open interval to be increased up to 15% (1. 3-1. 5 ms). 2.Mechanism of cylinder head assembly (Including suction muffler) The refrigerating effect every weight of R134a is more great than that of R12 because the evaporated residual heat of R134a is severe, but refrigerating capacity and EER have been decreased up to the order of 10-15% and 5-8% respectively because the specific volume of suction gas for R134a is more great than that for Rl2 and the circulated volume of refrigerant is small in the view of the compressor having the same displacement. In order to enhance the refrigerating capacity decreased like this, the suction muffler has been designed so as to have the mechanism isolating from heat and its assembly ability has been improved by assembling a capillary tube without using a screw. One of elements that effect the performance of a compressor the most powerfully is the condition of temperature and pressure for the suction gas. In order to improve this condition, the refrigerating capacity should be great by the increased of the circulated volume of refrigerants since the suction muffler was so designed in mechanism as shown in Fig 4 that the temperature of suction gas do not overheat. The details are as follows. As shown in Fig.5,the improved effect of performance by improving the temperature of suction gas can analyze the performance effect as the increase of specific volume to the temperature decrease of suction gas for the refrigerant Rl34a. 188

Under the standard condition of a calorimeter, specific volume Va is equal to 0. 211 m'/kg at the temperature T1 of 32. zoe for suction gas. Here,when the temperature of conventional and new model suction gas are considered as Tlc and Tln respectively, the effects have become.6.t= Tlc - Tln = 21.5 t and LlV= Vlc - Vln = 0. 019 m'/kg. As the circulated volume of refrigerant became increased by the above improvement in design, the refrigerating capacity and EER have been progressed up to about 8% and 4% respectively. For a compressor, something more important than the improvement of efficient is the design for low noise, and so the effect improving noise by applying the above suction muffler can be explained as follows. As noise peaks at 410 KHz in consequence of analying noise by changing design for the mechanism of apparatus, the design for resonance mechanism that can decrease this phenomenon has been emphasised. According to the sonic feature for R134a within muffler and the change of design for resonance mechanism, the peak of noise can be improved from 37. 2 db (A) to 29. 6 db (A) at the low frequency of 410 KHz. 3. Improvement of motor-efficient For a compressor, it is important to increase the efficient of a motor for improving the consumption input. In order to increase the efficient of a motor like this, decreasing the iron or copper loss is necessary and also the effort to develop materials for motor or decrease the starting torque is required. Otherwise, there is the way to design by increasing stack height and to improve the consumption input by increasing main winding. However, the difficulties in application by the increased cost have been followed up when developing and mass-producing the up-graded materials. Therefore, the specification for main and sub-winding has been improved, the iron loss has been minimized by optimizing the size of rotor slot in order to minimize increasing the cost of materials and enhance the efficiency of a motor, and the loss of no load has been improved up to 3.4W and so efficiency has been progressed up to 0. 9% by the optimum design (WM=WS) of running capacitor. Here, WM and WS mean the main loss and the sub loss of copper respectively calculated by the equation of! 2 R. 189

Especially, when designing a motor optimally by using current density, the best efficiency and performance can be shown by maintaining the current density of mainand sub-side for the model applying running capacitor with the order of 1.5-2.0. When selecting materials for a motor,materials to be compatible with the refrigerant of R134a shall be selected. Especially, the winding coi Is used for the existing refrigerant of R12 can not be used for a compressor using the refrigerant of R134a because that winding coils contains the wax components of paraffine. So,a compressor using R134a shall use the self-lubricated winding coils and ESTER components shall be used as the wax for lubrication. 4.Selecting the refrigeration oil for R134a. The refrigeration oi 1 for a compressor has acted the part of lubrication to minimize the friction and wear of moving part and sealing to prevent the leakage of refrigerant gas from the high pressed side to low pressed side. Especially, the oi I of a refrigerator having the most sui table feature lo the kind of refrigerant and the type of a compressor shall be selected because the feature of refrigerator's oi 1 for a compressor has changed contrary to the use of oi 1 alone. The refrigeration oil shall have such several features that miscibi 1i ty is good at low temperature and chemical reactions do not occur in spite of contacting with refrigerant at high temperature,but it is important to select the oil of low viscosity that reliance has been assured in order to enhance the efficiency of a compressor. As the machinery efficiency has been decreased by such loss as friction between shaft and bearing, friction between piston and wall of cylinder in a compressor, the new 15 grade oil developed from the existing 32 grade oil has been applied for this improvement of efficiency. Because the machinery efficiency was inhanced by applying the oil of low viscosit~eer could be improved up to 2% or more. For selecting the oil of low viscosity, it is the most important to assure the reliance of a compressor.as the viscosity of 15 grade oil is decreased less than 5 est at 100 ~'it is necessary to evaluate the accurate wear for the essential parts of moving area by making a compressor progress the long term reliance test under the continuous over load operating condition. For a compressor using the refrigerant of R134a particullary, the counter measures on such failures as blocking the capill,ary tube are required acutely. 190

In case of using the anti-wear additive ( P,S,Cl,etc) in order to increase the wear -proof of such boundary lubricating parts as piston, such additive mainly have caused blocking the capillary tube, it is necessary to determine the components and quantity of an additive so that a failure like capillary blocking does not occur. CONCLUSION By developing a compressor for the above refrigerant of R134a, the following effects could be found out. (1) As a result of applying this refrigerant to the domestic refrigerator, we could find the amount of electrical energy consumption to be decreased up to 10 % or more and ourselves to be corresponded to the energy saving policy and contributed to the protection of environment of government. (2)We could exact right the theory related to develop the high efficiency compressor for R134a and accumulate data from the various experiments. (3)we could accumulate the basic technology for the application of refrigerant R134a and improve the applicable technology for production. ( Reference ) l.nlkawahira; THE HERMETIC TYPE OF A COMPRES~oR, JAPANESE REFRIGERATING ASSOCIATION, 1981, PP. 3-13. 2. uanalysis REPORT FOR ALTERNATIVE REFRIGERANT R134a.,SAMSUNG SUNG ELECTRONICS CO. LIVING SYSTEM RESEARCH CENTER, 1992. 3. RAY SCHMITZ; "NEW HIGH EFFICIENCY R134a COMPRESSOR.PROCEEDINGS OF THE 1994 INTERNATIONAL COMPRESSOR ENGINEERING CONFERENCE AT PURDUE; JULY 1994,PP.393-401 4. ASHRAE, "METHOD FOR PRESSURE MEASUREMENT, ANSI/ASHRAE STANDARD 41.3-1982 5. H.J.KIM; compressor DESIGN & PERFORMANCE ANALYSis, INTERNATIONAL INDUSTRY INFORMATION SYSTEM, 19 91. 6. ANDREW D.ALTHOUS~CARL H. TURNQUIST,ALFRED F.BRACCIANO; REFRIGERATION AIRCONDITI ONING 191

p R E s u R E ---:Theoretical compression cycle ---:CONVENTIONAL. MODEL -------- :NEW MODEL Improving the loss of over pressure ~p = Pl- P2 = 3.2 kg/ad.g VOLUME <FIG 1> P-V DIAGRAM p --NEW MODEL (NK SERIES) --CONVENTIONAL MODEL ~ t,j. <FIG 2>VALVE PLATE TD TIME <FIG 3>Comparison of discharge valve system T2 p h <FIG.4> SUCTION MUFFLER MECHANISM < FIG 5 > P - h DIAGRAM 192